The Elevated Central Chemosensitivity in Obstructive Sleep Apnea Patients with Hypertension

Urinary Epinephrine Sulfate Can Predict Cardiovascular Risk in Moderate-to-Severe OSA: A Metabolomics-Based Study

Purpose

There are currently no ideal indicators for predicting the cardiovascular risk of obstructive sleep apnea (OSA). This study aimed to employ urinary metabolomics to detect early cardiovascular risk in patients with moderate-to-severe OSA.

Patients and Methods

Male participants who underwent polysomnography from November 2020 to May 2021 were screened. Clinical data, polysomnography data and urine samples were collected. Untargeted metabolomics analyses of urine were performed. Multivariate analyses and receiver operating characteristic (ROC) curve analyses were subsequently performed to identify potential biomarkers. Associations between metabolites and clinical indicators and cardiovascular risk were examined through linear regression analyses with interaction and mediation analyses.

Results

Thirty-six male participants were included in the study, comprising 22 males with moderate-to-severe OSA and 14 age-matched controls, with an average age of 39.6 ± 9.2 years. We identified 65 metabolites in the study, involving pathways including pyrimidine, androgen, estrogen, vitamin B6 and sulfate/sulfite metabolism. Among them, epinephrine sulfate was the most significantly altered metabolite. ROC analyses highlighted that epinephrine sulfate had the highest area under the curve (AUC=0.883) for detecting moderate-to-severe OSA. Epinephrine sulfate was statistically correlated with OSA severity, hypoxia-related indicators (apnea-hypopnea index: r=0.685; oxygen desaturation index: r=0.743, p<0.0001), arterial stiffness (arterial augmentation index: r=0.361, p=0.031) and long-term cardiovascular risk (Framingham cardiovascular risk: r=0.375, p=0.024). Linear regression analysis revealed that epinephrine sulfate was significantly associated with an increased in the Framingham risk (β = 0.004, 95% CI = 0.000-0.009, p = 0.049), with the effect partly mediated by systolic blood pressure (27.6%) and not moderated by other factors. Additionally, it also significantly associated with the increased in the arterial augmentation index (β = 0.019, 95% CI = 0.000-0.037, p = 0.046), with the effect fully mediated by blood pressure and not moderated by other indices statistically.

Conclusion

There are significant metabolic pathway alterations in moderate-to-severe OSA patients. Urinary epinephrine sulfate markedly predicts early cardiovascular risk in OSA patients.

Nocturnal urination is associated with the presence of higher ventilatory chemosensitivity in patients with obstructive sleep apnea

PURPOSE

Chemosensitivity is an essential part of the pathophysiological mechanisms of obstructive sleep apnea (OSA). This study aims to use the rebreathing method to assess hypercapnic ventilatory response (HCVR) and analyze the association between chemosensitivity and certain symptoms in patients with OSA.

METHODS

A total of 104 male patients with diagnosed OSA were enrolled. The HCVR was assessed using rebreathing methods under hypoxia exposure to reflect the overall chemosensitivity. Univariate and multivariate linear regression were used to explore the association with chemosensitivity. Participants were enrolled in the cluster analysis using certain symptoms, basic characteristics, and polysomnographic indices.

RESULTS

At similar baseline values, the high chemosensitivity group (n = 39) demonstrated more severe levels of OSA and nocturnal hypoxia than the low chemosensitivity group (n = 65). After screening the possible associated factors, nocturnal urination, rather than OSA severity, was found to be positively associated with the level of chemosensitivity. Cluster analysis revealed three distinct groups: Cluster 1 (n = 32, 34.0%) held younger, obese individuals with nocturnal urination, elevated chemosensitivity level, and very severe OSA; Cluster 2 (41, 43.6%) included middle-aged overweighted patients with nocturnal urination, increased chemosensitivity level, but moderate-severe OSA; and Cluster 3 (n = 21, 22.3%) contained middle-aged overweighted patients without nocturnal urination, with a lowered chemosensitivity level and only moderate OSA.

CONCLUSION

The presence of nocturnal urination in male patients with OSA may be a sign of higher levels of ventilatory chemosensitivity, requiring early therapy efforts independent of AHI levels.

The potential interaction between chemosensitivity and the development of cardiovascular disease in obstructive sleep apnea

OBJECTIVES

Chemosensitivity is an essential part of the pathophysiological mechanisms of obstructive sleep apnea (OSA). Not only does OSA have a certain relationship with the comorbidity of cardiovascular disease (CVD) but also chemosensitivity plays a crucial role in the development of CVD. This study aims to investigate the potential interaction between chemosensitivity and the development of CVD in OSA.

METHODS

A total of 169 participants with suspected OSA were included. Data were gathered on the parameters of polysomnography and baseline clinical features. Peripheral chemosensitivity was evaluated by employing the rebreathing test. The lifetime CVD risk was computed using the China-PAR (Prediction for atherosclerotic CVD Risk in China) risk equation.

RESULTS

After controlling for covariates, participants with chemosensitivity levels in the second and fifth quantiles tended to hold an increased proportion of high lifetime CVD risk (OR 10.90, 95%CI [2.81-42.28]; OR 6.78, 95%CI [1.70-27.05], respectively). The diagnosis of OSA would significantly increase the 10-year and lifetime CVD risks in participants with low chemosensitivity, while no such differences were found in participants with high chemosensitivity.

CONCLUSION

Higher lifetime CVD risk was associated with participants who had greater peripheral chemosensitivity. In terms of the CVD outcomes, adult patients with a relatively low level of chemosensitivity may be primarily related to their diagnosis of OSA, whereas adult patients with a relatively high level of chemosensitivity may be more strongly associated with their elevated levels of chemosensitivity rather than OSA.